iwlwifi: set VHT beamformee STS cap correctly

It was set to zero which reflects support of a single STS.
Set according to the number of Rx antennas which correctly
reflects the number of STSs the STA can receive in a VHT NDP.
This improves beamforming and has been tested to improve Rx
throughput.
Signed-off-by: Eyal Shapira <eyal@wizery.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/iwlwifi/iwl-nvm-parse.c

@@ -263,11 +263,14 @@ static void iwl_init_vht_hw_capab(const struct iwl_cfg *cfg,
 				  struct iwl_nvm_data *data,
 				  struct ieee80211_sta_vht_cap *vht_cap)
 {
+	int bf_sts_cap = num_of_ant(data->valid_rx_ant) - 1;
+
 	vht_cap->vht_supported = true;
 
 	vht_cap->cap = IEEE80211_VHT_CAP_SHORT_GI_80 |
 		       IEEE80211_VHT_CAP_RXSTBC_1 |
 		       IEEE80211_VHT_CAP_SU_BEAMFORMEE_CAPABLE |
+		       bf_sts_cap << IEEE80211_VHT_CAP_BEAMFORMEE_STS_SHIFT |
 		       7 << IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_SHIFT;
 
 	if (iwlwifi_mod_params.amsdu_size_8K)